12th International Symposium on District Heating and Cooling

The <strong>12th</strong> <strong>International</strong> <strong>Symposium</strong> on District Heating and Cooling,September 5 th to September 7 th , 2010, Tallinn, EstoniaHeat lossThe snow did not melt over the pipes in the test area. Ifone would study other older district heating pipes theywould reveal themselves by melting the snow overthem. This effect never happened in the test area.The acceleration and vibration velocity are alsonegligible under the traffic load from e.g. a heavy lorry.Probably there will be no problems using graphitegaskets also with only 200 mm of coverage.The casaflex pipe is prolonging itself if it may but theforce with which it is prolonging itself is but a fraction ofwhat comparable ordinary steel pipes uses. This effectmakes it more suitable for shallow shafts.It is possible to combine different leak indicatorsystems and still get the TDR-graphs. The graphs donein this test indicates that there are no leaks in theoperating pipes after one year.Fig. 24 Left; Test area in January, Right; Test area inFebruary.The demanded levels for the degree of compaction ofthe street are possible to reach also with a d.h. pipe60 mm below the surface as it gets compressedwithout hurting the pipe.There are still other issues that can be considered thatare not included in the tests presented in this paper,aspects as e.g. heat losses.5. ACKNOWLEDGEMENTFig. 25 Left Test area in March, Right; D. H. chamberrevealing itself in February.However the heat loss is of course bigger comparedwith normal standard because of that the pipes areplaced closer to the air.Frost action damagesIn theory one could imagine that the street on bothsides of the district heating pipe would erect during thewinter if there were soil that could frost heave. Thiscould of course damage the asphalt. But streets are notsupposed to be built with soil that could frost heave. Sothere should not be any problem.There was no notable difference in the height of thestreet over the district heating pipes compared to thestreet beside the test area during the winter.4. CONCLUSIONThe article probably describes the first operating d.h.pipes placed in backfill of 0-40 only 200 mm below thesurface in a street with heavy traffic. As expected, thepipes are working nicely. The loads that have beenmeasured are acceptable or even low for the d.h. pipe.As it seems also the street is satisfactory working eventhough there are d. h. pipes close to the surface.The pipe deformations are negligible with respect to thepipes function both over time and under an instanttraffic load.The authors would like to express their appreciation toa couple of key persons. There had been no test ofthis kind without their support and permitting. Thepersons are:– Mr. Bo Andersson Planing Manager atTrafikkontoret Göteborgs Stad,– Mr. Lars Ljunggren Manager at GöteborgEnergi AB and– Mr Göran Johnsson Technical Manager atPowerpipe Systems AB.6. REFERENCES[1] Molin J., Bergström G. and Nilsson S. (1997).Kulvertförläggning med befintliga massor, SwedishDistrict Heating Association FOU 1997:17, (inSwedish)[2] Bergström G., Nilsson S. and Sällberg S-E. (2001),Täthet hos skarvar vid återfyllning med befintligamassor, Swedish District Heating Association FOU2001:58, (in Swedish)[3] Nilsson S, Sällberg S-E, Bergström G, (2006)Grund förläggning av fjärrvärmeledningar, SwedishDistrict Heating Association FOU, FOU Värmegles,2006:25, (in Swedish)[4] Gudmundson T. ÅF-Processdesign AB, (2002),Casaflex-rör i Malmö 2001,. Swedish DistrictHeating Association, FVF 021241, (in Swedish)103